P49.11: Prediction of preterm delivery in threatened preterm labor: comparison between ultrasonographic cervical length measurement and digital examination

To compare ultrasonographic cervical length measurement and digital examination as a prognostic factor for progression to preterm birth in cases of threatened preterm labor. Ultrasonographic cervical length measurement and digital cervical examination was carried out in 154 women with singleton pregnancies presenting with threatened preterm labor and intact membranes at 24 to 33 + 6 weeks of gestation. Other potential prognostic factors, such as previous history of preterm delivery, parity, BMI, administration of tocolytics were assessed. The outcomes of the study were delivery within 7 days of presentation and delivery before 37 weeks gestation. The median gestation at presentation was 30 (range, 24+ to 33 + 6) weeks and the median cervical length was 29 (range, 3.1 to 52.1) mm. Delivery within 7 days of presentation occurred in 11% (17/154), delivery before 37 weeks occurred in 40.9% (63/154) and these were inversely related to cervical length. Receiver-operating characteristics (ROC) curves established a cervical length of 25 mm as the most relevant cut-off level for prediction of delivery within 7 days. The risk of delivery within 7 days was significantly increased when the Bishop score was greater than or equal to 6 (OR = 7.13; 95% CI, 1.44–35.12, P = 0.03) or when ultrasonographic cervical length was less than or equal to 25 mm (OR = 44.89; 95% CI, 5.75–350.72, P < 0.0001). But logistic regression analysis demonstrated that the significant independent risk factors were cervical length less than or equal to 25 mm (OR = 76.59; 95% CI, 6.41–914.64, P = 0.001) and administration of tocolytics (OR = 0.03; 95% CI, 0.003–0.3, P = 0.04). For delivery before 37 weeks, only independent predictor was cervical length. Ultrasonographic cervical length measurement is a useful predictive tool for progression to preterm delivery compared to digital examination in women with threatened preterm labor.